The present invention relates to back constructions with flexible lumbar support, such as may be used not only for chairs and furniture seating, but also in vehicle and vessel seating (personal and mass-transit, including automobiles, trucks, buses, planes, trains, boats, etc.), stadium and auditorium seating, bench and multi-person seating, and other seating arrangements.
A comfortable and ergonomic back construction is disclosed in Battey et al. U.S. Pat. No. 5,871,258 (hereafter the “Battey '258 patent”). The back construction in the Battey '258 patent includes a back shell pivoted to a back frame at top pivots and at forwardly-located bottom pivots, and includes a flexible lumbar section that combines with stiff thoracic and pelvic sections and the pivots to cause the back to flex along a well-defined predetermined path. A biasing mechanism biases the lumbar section forwardly for optimal support to a seated user. Notably, in the Battey '258 patent, the bottom pivots are located on flanges (134) that extend forward of a front surface of the back shell, in a position where they limit overall design options and potentially interfere with laterally sliding onto the seat from a side position. It is desirable in some environments and some seating applications to eliminate interference to lateral entry onto the seat caused by the forwardly-extending flanges. At the same time, it is desirable to maintain the ergonomic function and comfortableness of a flexible back shell construction similar to the one shown in the Battey '258 patent.
It has been discovered that back supports with very flexible lumbar regions can potentially have issues caused by “uncontrolled flexure”. Specifically, under extreme conditions, a highly flexible back support may bend in ways that do not represent human shapes, such as “S” shapes or non-arcuate “non-human-like” shapes. The reason this is important is because non-human-like shapes cause localized uncomfortable pressure in the back and/or lines of uncomfortably high pressures in the back. The original Leap® chair designs (e.g. see Battey U.S. Pat. No. 5,871,258, FIG. 12) attempted to solve this problem of bending to “non-human-like” shapes by providing forwardly-curved back shell material with first pivot points near the upper back and second pivot points forward of the lower pelvic (or belt) area. However, it is desirable to better control flexure of the back shell with fewer design constraints in regard to pivot locations, and while at the same time simplifying overall construction and design of a back shell and while reducing components and assembly time. It is also desirable to provide a back support design that is made of environmentally friendly materials, and made of easily recyclable components.
Heidmann U.S. Pat. No. 6,616,228 discloses a back arrangement where a flexible back shell is pivotally mounted at a top location and pivotally/slidably supported at a bottom location. However, testing has shown that better control over flexure of the back shell and better control over movement of and orientation of a lower edge of the back shell may be desired, while also requiring fewer design constraints in regard to pivot locations, and while at the same time simplifying overall construction and design of a back shell and while reducing components and assembly time.
Also, increased design flexibility is desired for both aesthetic and functional aspects, such as to allow relocation of or elimination of the top and/or bottom pivots, while maintaining a relatively simple mechanical assembly, while using environmentally-friendly parts that can be readily disassembled and recycled, and while still providing an open lateral access path into the seating area in front of the back.
Thus, a system having the aforementioned advantages and solving the aforementioned problems is desired.